With the approach of summer, many of the animals at the Jerusalem Biblical Zoo are enjoying the warmer weather, perhaps none more so than the zoo's pair of white rhinoceroses, Gilad and Karmi. Karmi, who is 13, and Gilad, two years older, usually spend the cold winter months confined inside their shelter; but now they are out and about roaming the large enclosure that they share with the giraffes and zebras. Although they may look similar, not all rhinos are created equal, especially regarding the size of their horns. Karmi has a long straight horn, while Gilad's is shorter and thicker. The horns consist of stiff keratin, similar to hair. In fact, it is their much sought-after horns that nearly led rhinos to extinction. In many traditional Asian medicines, rhinoceros horns are used to cure fevers and convulsions, and poachers hunt the animals for their valuable horns. Aside from repopulation and preservation programs, wildlife organizations are working to persuade practitioners of traditional medicines to use other ingredients in their potions. There are two species of white rhinos, both of which come from Africa. Northern White Rhinoceroses have been hunted almost to extinction, with less than 15 of them left in the world. The Southern White Rhinoceros has fared better, due largely to more effective measures against poaching in South Africa and other southern African countries. Nonetheless, the species is still in danger, and zoos around the world are actively engaged in breeding it. So much importance is placed on breeding, that zoos are allowed to keep only female white rhinos when there is an optimal breeding ratio of at least two females for every male. Due to the limited housing facilities at the Jerusalem Biblical Zoo, Karmi and Gilad remain without female company; there isn't enough space to keep two females for each of these heavyweights. Taking care of animals that weigh twice as much as the average family car is a challenge, yet the most effective tool for rhino taming is nothing more threatening than a toilet brush. According to chief herbivore keeper Gilad Shalom, rhinos love being tickled behind the ears with a toilet brush. Rhinos are bleary-eyed creatures with poor eyesight, but they have keen hearing and an excellent sense of smell, which they use to sniff out the grass, shrubs and bushes they eat. The rhinos can be seen all day at the zoo either resting in the sun, eating or wallowing in the mud beside their enclosure's large pool of water.